constellation/internal/imagefetcher/imagefetcher.go

153 lines
4.1 KiB
Go

/*
Copyright (c) Edgeless Systems GmbH
SPDX-License-Identifier: AGPL-3.0-only
*/
/*
Package imagefetcher provides helping wrappers around a versionsapi fetcher.
It also enables local image overrides and download of raw images.
*/
package imagefetcher
import (
"context"
"encoding/json"
"errors"
"fmt"
"io/fs"
"regexp"
"github.com/edgelesssys/constellation/v2/internal/api/fetcher"
"github.com/edgelesssys/constellation/v2/internal/api/versionsapi"
"github.com/edgelesssys/constellation/v2/internal/attestation/variant"
"github.com/edgelesssys/constellation/v2/internal/cloud/cloudprovider"
"github.com/spf13/afero"
)
// Fetcher fetches image references using a lookup table.
type Fetcher struct {
fetcher versionsAPIImageInfoFetcher
fs *afero.Afero
}
// New returns a new image fetcher.
func New() *Fetcher {
return &Fetcher{
fetcher: versionsapi.NewFetcher(),
fs: &afero.Afero{Fs: afero.NewOsFs()},
}
}
// FetchReference fetches the image reference for a given image version uid, CSP and image variant.
func (f *Fetcher) FetchReference(ctx context.Context,
provider cloudprovider.Provider, attestationVariant variant.Variant,
image, region string,
) (string, error) {
ver, err := versionsapi.NewVersionFromShortPath(image, versionsapi.VersionKindImage)
if err != nil {
return "", fmt.Errorf("parsing config image short path: %w", err)
}
imgInfoReq := versionsapi.ImageInfo{
Ref: ver.Ref(),
Stream: ver.Stream(),
Version: ver.Version(),
}
url, err := imgInfoReq.URL()
if err != nil {
return "", err
}
imgInfo, err := getFromFile(f.fs, imgInfoReq)
if err != nil && errors.Is(err, fs.ErrNotExist) {
imgInfo, err = f.fetcher.FetchImageInfo(ctx, imgInfoReq)
}
var notFoundErr *fetcher.NotFoundError
switch {
case errors.As(err, &notFoundErr):
overridePath := imageInfoFilename(imgInfoReq)
return "", fmt.Errorf("image info file not found locally at %q or remotely at %s", overridePath, url)
case err != nil:
return "", err
}
if err := imgInfo.Validate(); err != nil {
return "", fmt.Errorf("validating image info file: %w", err)
}
return getReferenceFromImageInfo(provider, attestationVariant.String(), imgInfo, filters(provider, region)...)
}
func filters(provider cloudprovider.Provider, region string) []filter {
var filters []filter
switch provider {
case cloudprovider.AWS:
filters = append(filters, func(i versionsapi.ImageInfoEntry) bool {
return i.Region == region
})
}
return filters
}
func getFromFile(fs *afero.Afero, imgInfo versionsapi.ImageInfo) (versionsapi.ImageInfo, error) {
fileName := imageInfoFilename(imgInfo)
raw, err := fs.ReadFile(fileName)
if err != nil {
return versionsapi.ImageInfo{}, err
}
var newInfo versionsapi.ImageInfo
if err := json.Unmarshal(raw, &newInfo); err != nil {
return versionsapi.ImageInfo{}, fmt.Errorf("decoding image info file: %w", err)
}
return newInfo, nil
}
var filenameReplaceRegexp = regexp.MustCompile(`([^a-zA-Z0-9.-])`)
func imageInfoFilename(imgInfo versionsapi.ImageInfo) string {
path := imgInfo.JSONPath()
return filenameReplaceRegexp.ReplaceAllString(path, "_")
}
// getReferenceFromImageInfo returns the image reference for a given CSP and image variant.
func getReferenceFromImageInfo(provider cloudprovider.Provider,
attestationVariant string, imgInfo versionsapi.ImageInfo,
filt ...filter,
) (string, error) {
var correctVariant versionsapi.ImageInfoEntry
var found bool
variantLoop:
for _, variant := range imgInfo.List {
gotCSP := cloudprovider.FromString(variant.CSP)
if gotCSP != provider || variant.AttestationVariant != attestationVariant {
continue
}
for _, f := range filt {
if !f(variant) {
continue variantLoop
}
}
correctVariant = variant
found = true
break
}
if !found {
return "", fmt.Errorf("image not available in image info for CSP %q, variant %q and other filters", provider.String(), attestationVariant)
}
return correctVariant.Reference, nil
}
type versionsAPIImageInfoFetcher interface {
FetchImageInfo(ctx context.Context, imageInfo versionsapi.ImageInfo) (versionsapi.ImageInfo, error)
}
type filter func(versionsapi.ImageInfoEntry) bool